Monday, April 29, 2013

Not all corn farmers and agronomists feel that planting date is a significant yield impact factor. However, in the northern Corn Belt delayed planting not only lowers potential grain yield as described previously, but it can have a significant impact on the economics of corn production. Growing season weather ultimately determines the impact of drying costs on corn production economics. Farmers in the northern Corn Belt often face a shorter growing season with cool, wet conditions and significant snowfall earlier and more often than farmers in the central and southern Corn Belt. During the 2009 production season, drying costs often approached $1.00 per bushel.

When energy costs are zero, such as for high moisture corn, then farmers only consider yield impacts with delayed planting. Table 1 can be used to calculate the impact of energy costs on corn grain drying using an energy:grain price ratio. As energy price increases the energy:corn price ratio increases. As corn price increases the energy:corn price ratio decreases. We assume that it takes 0.02 gallons of LP gas to lower a bushel of corn 1% grain moisture (Hoeft et al, 2000; Hallevang and Morey). Over the last few growing seasons LP gas has cost about $1.60 to $2.00 per gallon while corn prices have ranged from $5 to $7 per bushel resulting in energy:corn price ratios of 0.005 to 0.008.

The energy:grain price ratios described in Table 1 are used to calculate the amount of grain yield that is required to pay for energy costs related to drying with delayed planting date in Figure 1. When the energy costs are zero, then the relationship is the same as the grain yield function described previously. As the energy:grain price ratio increases, it takes more and more bushels per acre to pay for the drying costs. For example, on June 1 the grain yield of a 104-108 d RM hybrid is 169 bu/A and the grain moisture 31%. If the energy:grain price ratio is 0.010, then only 143 bu/A are actually harvested. The difference of 26 bu/A was used to pay for the energy costs to dry the corn to 15.5% moisture.

Figure 1. Remaining grain yield (bu/A) after paying the energy cost for drying at various Energy:Corn price ratios. The regressions for grain yield and grain moisture have been fitted to full-season hybrids (104-108 d RM) grown during 2003-2012 (N= 208) at Arlington, WI.

Farmers manage this situation by switching hybrid maturity, switching to different crops or leaving the field over winter to harvest the following spring once grain has dried sufficiently. All options can have significant impact on profitable corn production.

So whether it is a conundrum or fear-mongering, the fact remains that in the northern Corn Belt we are often limited by our growing season and planting date has a significant effect on corn grain yield and more importantly production economics. It is expensive to produce wet corn and the odds of it happening increase as planting date is delayed.

Further Reading

Monday, April 22, 2013

This year farmers have been challenged by cool, wet conditions during April. Snow is again forecast for later this week. Even though planting dates seem like they have been delayed, especially compared to 2012, we still have not passed the optimum planting dates for corn. Wisconsin farmers can plant a large number of acres quickly. Since 1979, there have been 5 years when 40% or more of the acres were planted in one week (1981, 1984, 1999, 2000, and 2004). Between May 2-9, 1999 and April 30-May 7, 2000 farmers planted 1.5 million acres in one week (42% and 44% of the acres planted in those years).

At the University of Wisconsin Agricultural Research Station in Arlington, we have established planting date trials since 1974. Multiple hybrids are established as soon as field conditions allow. In many years, snow is still in roadside ditches when the first planting date occurs. I pooled data for full-season hybrids with Relative Maturity ratings of 104 to 108 RM for the last 10 years (2003-2012).

The corn grain yield response to planting date is shown in Figure 1. The planting date producing maximum grain yield during this period is April 28. Yields were within 95% of the maximum yield from April 15 to May 12, a 28-day period. By May 10 grain yield is decreasing 0.9 bu/A per day and then accelerates to 2.6 bu/A per day on June 1. Grain yield risk (the spread of the data points around the regression line) is lowest in April and early May at + 14 bu/A and increases to + 45 bu/A in late May and early June.

Year affects the planting date when maximum yield occurs, the date of 95% maximum yield, and the yield loss acceleration during late May and early June (Table 1). The date when maximum yield occurs varies from April 10 to May 3. We were still within 95% of the maximum until April 29, 2005 and May 19, 2011.

Like last year the important thing to remember is patience. Be ready to go so that when field conditions are fit, you are ready to plant. Our standard planting date recommendation is to plant as quickly and safely as possible after April 20 in southern Wisconsin, and after April 30 in northern Wisconsin.